The participating cardiologist and cardiovascular surgeons from Mayo Clinic will work with the other Bypass Angioplasty Revascularization Investigation (BARI) members and NHLBI staff during Phase I to develop a final protocol for a multicenter trial that will test in a prospective randomized trial if percutaneous transluminal coronary angioplasty (PTCA) is associated with similar relief of angina pectoris as coronary artery bypass graft surgery (CABGS) in patients with multivessel coronary artery disease without an increased risk of death or myocardial infarction and is performed with long-term lower socioeconomic cost. This trial will also test if, in comparable patients with multivessel coronary artery disease, PTCA (even with less complete revascularization) is equal to CABGS in maintaining survival and protecting against disabling angina pectoris and myocardial infarction. During Phase 2, Mayo Clinic will enroll 150 patients with angiographic demonstration of at least two major epicardial arteries with 70% or more obstruction suitable for both PTCA and CABGS who will be randomized to either PTCA or CABGS. All patients with known or suspected ischemic heart disease undergoing coronary angiography at Mayo Clinic during the recruitment period will be asked to participate in a BARI registry. This group of patients will make it possible to determine the validity of observations from the randomized group of patients to a broader group of patients receiving PTCA and CABGS. All patients will be followed for at least a 4-year period. The organization of the study will include a Data Coordinating Center, a Central Angiographic Laboratory, and clinical units. There will be a Steering Committee composed of investigators from all components of the study to direct the scientific aspects of the study and a Data Monitoring Committee that will be comprised of experts not directly involved in the study to monitor the data during the recruitment period while the investigators are blinded to the data. Even if PTCA is proven to be a comparable alternative revascularization procedure only for a minority of patients with ischemic heart disease who are now receiving coronary artery bypass graft surgery, potential for health care cost containment could be great.